Bonded non-metallic tie plate



1967 c. J. PENNINO ETAL 3,358,925

BONDED NON-METALL IC TIE PLATE Filed June 28, 1966 FIG. I

Z INVENTOR5 amass J. PENN/N0 4! BY M0555 m ammo/20 United States Patent ABSTRACT OF THE DISCLOSURE A non-metallic tie plate is adhesively bonded to a Wooden railroad tie to completely seal the interface between the tie and the tie plate. The tie plate comprises a non-flowable crosslinked plastic material that is substantially non-permanently deformable under the weight of a train passing over the rail supported by the tie and tie' plate.

This invention relates to railroad tie plates. More particulariy, this invention relates to a non-metallic tie plate which is adhesively bonded to the tie.

Metal tie plates have been used beneathrails to spread the load or weight transmitted from the rail to the tie over a larger area of the tie surface. Holes are usually provided in such a metal tie plate and the rail is secured to the tie by spikes which are driven through the holes in the tie plate.

While such metal tie plates have been used for years, this arrangement has not been fully satisfactory. For example, the interface between the metal tie plate and the wooden tie is subject to plate cutting. To reduce plate cutting, the metal tie plates have been made wider and wider. However, even though tie plates have grown from to 16" in width, the plate still cuts the ties. Mechanisms which cause plate cutting by metal tie plates includes the following:

Spikes are usually not driven tight, approximately A" of play is often specified. Even if they were driven tightly, the wave action caused in the track by the passage of trains would tend to loosen them.

The looseness allows water to get under the tie plate from rain, melting snow or from condensation from the atmosphere when the plate is cooler than the air. This looseness allows dust and abrasive particles from the road bed raised by the air movement of passing trains and natural winds to get under the tie plate. The water trapped under the tie plate and on the wood interface softens the topmost wood fibers and makes it easier for the movement of the tie plate to abrade the wood. For each increase of 1% moisture content up to the fiber saturation point (about 30% moisture content) wood loses 2 /z% of its side hardness strength and about 5 /2% of its strength in compression perpendicular to the grain (p. 85, Handbook 72, United States Department of Agriculture). In addition to the above physical degradation, some authorities believe that the oxidative products of ferrous metals cause a chemical degradation of wood at a slow rate.

Another disadvantage of the metal tie plate is that the sideways bufieting of the passing train on a curve is transmitted to one or a few spikes and through them to end grain of Wood only /s or 1 across. This enlarges the spike holes, allows the rails to lose their gage, i.e. separate slowly, until they have to be reset.

It has, therefore, been proposed by many to use some sort of resilient pad beneath the rail either as an adjunct to the metal tie plate or as a replacement for the metal tie plate. However, the use of such substitutions has always been coupled with the mechanical fastening of the rail and tie plate to the tie by spikes or the like. There- Patented Dec. 19, 1967 "ice fore, although some of the problems which arise with the use of metal tie plates have been mitigated by the substitution of more resilient materials other problems have not been solved. The lack of a bond between the tie plate and the tie allows the deleterious effects of water and dirt or sand and the like to attack the tie.

We have discovered a non-metallic tie plate that may be bonded directly to the tie and held by an adhesive without the need for spikes and the like. The rail may then be placed directly on the non-metallic tie plate without being held thereto.

In accordance with this invention, a tie is provided having a non-metallic tie plate adhesively fastened to an upper surface thereon, and rail holding means fastened to said tie at a spaced distance from the non-metallic tie plate, and the tie plate being held to the tie by an adhe- Sive bond between the tie plate and the tie.

The non-metallic tie plate comprises a plastic material which may be bonded to the wood either before or after the wood has been creosoted. The plastic material must be capable of maintaining its form and shape under pressure; that is it must not flow under the weight of the train passing over it as would many rubber and thermoplastic type plastics. The material should therefore be a thermosetting type material having a fair degree of crosslinking. However, modified thermoplastics which have been modified with cross-linking agents to exhibit the above physical characteristics may also be used.

In one embodiment the tie plate is cast from a polyurethane material having the following characteristics Tensile strength (ultimate) p.s.i 4,0008,000 Elongation at break percent 200600 Modulus at elongation p.s.i 1,4002,400 300% elongation p.s.i 2,4003,800 Compressive strength at- 10% deflection p.s.i 7001,500 20% deflection p.s.i 1,3002,400

Polyurethanes having the above characteristics are readily available from standard supply sources well known to those skilled in the art.

The polyurethane tie plate is then bonded to the wood by a resorcinol or epoxy adhesive. The epoxy is preferred when bonding over previously creosoted wood, although resorcinol adhesives have been successfully used with creosoted wood and have held for as long as twenty-five years.

In another embodiment a filled epoxy tie plate is utilized. This embodiment has the advantage that the material may be directly cast in place on the wood, only a prior gel coat being necessary.

Epoxies which we have successfully used have the following physical characteristics:

Deflection temperature at 264 p.s.i. C 60-70 Tensileystrength ultimate p.s.i 7,00010,000 Tensile moduls l0 p.s.i. 350-400 Elongation percent 3-6 Compressive strength at 50% deformation p.s.i 25,000-35,000

Epoxy resins having the above characteristics are readily available. For example, a Bisphenol-A Glycidyl ether such as Epon 828 may be blended with a polyarnide curing 0 agent such as Versamid and an expoxidized fatty acid viscosity reducing agent and flexibilizer such as Cardolite may be used with a tri-(dimethyaminomethyl) phenol catalyst in the following ratio:

Epon 828 parts by weight 100 Versamid 140 do 30 Cardolite do Catalyst, percent by weight of total resin 2 The above resin will cure in above 2 hours at 100 C. The above formulation may have an inert filler added if so desired. We have successfully used fillers such as sand, asbestos and the like. A sand filler may be used as high as 600 parts by weight sand per 100 parts by weight resin while an asbestos filler is quite effective in the ratio of parts by weight asbestos per 100 parts by weight resin. An additional benefit which accrues from the use of an epoxy resin is that the resin may be cast directly on the tie, rather than casting and bonding in two steps. In such a case, a first gel coat is applied and then the remainder of the resin is poured onto the tie. Mold forms, of course, must be used to retain the resin in its desired form until cured.

Other resin, such as polyesters, of course, may be substituted for the epoxies and urethanes previously discussed. However, theresin must have the cross-linked or thermosetting characteristics previously alluded to. The resin also must be one capable of being adhesively bonded to the wood tie surface to protect the wood surface.

Referring to the drawings:

FIG. 1 is an exploded view of the non-metallic tie plate and the components with which it cooperates;

FIG. 2 is a cross-sectional view illustrating an alternate construction of the tie plate.

Referring now to FIG. 1, a tie 2 is shown which is generally similar to those now employed in railroad track.

A conventional rail 50 is shown, and it will be understood that generally two such rails are secured to each tie at a spaced distance apart from one another to form the gauge of the track.

Tie 2 has a rectangular groove generally indicated at 4 transversely cut into its upper surface. Sidewalls 30 and 40 of groove 4 extend to a depth of about A to 1". The groove may, however, extend to a greater depth, depending upon the strength of the wood tie. However, it has been found that 1 depth is usually more than adequate for the desired result presently to be described.

The non-metallic tie plate 10, when cast as a separate member, is formed as a generally rectangular slab having a length corresponding to the width of the tie (and therefore the length of slot 4) and a width sufficient to provide a snug fit between plate 10 and groove walls 30 and 40 when the plate is fitted to groove 4. The lower surface of plate 10 is generally flat so as to cooperate with flat bottom wall 44 of groove 4.

However, if a larger bonding surface is desired, without increasing the load bearing surface, both the lower surface of plate 10 and bottom wall 44 may be formed with irregular surfaces such as small grooves or a wattle design.

Plate 10 is fitted into groove 4 and, when cast separately, is secured thereto by a resorcinol based adhesive to form a strong bond between the non-metallic tie plate and the wood.

Plate 10 is formed with slotted upper surface 16 thereon. The width of slot 16 corresponds with the width of rail flange 52 which snugly fits therein. Raised portions 32 and 42 form the sidewalls of slot 16 and engage both the rail flanges on their inner edge and sidewalls 30 and 40 respectively on their outer edges. Thus, the combined widths of raised portions 32 and 42 is equal to the width of groove 4 minus the width of rail flange 52. This enables raised portions 32 and 42 to form the gauge retaining the standard width between rails, yet provide a cushioning effect against the sidethrust of the wheels of a train passing over the rail-especially on a curve. This is in marked 4 contrast to the prior art methods of metal spikes and raised lips on metal tie plates to retain the rail in gauged position.

Rail 50 is secured to tie 2 against upward motion by means of a spring-type clamp 60 which may be mounted on tie 2 on both sides of rail 50. Clamp 60 has an extended portion 62 which presses down on the upper surface of flange 52.

It should be noted here that the clamp does not hold the tie plate in place-or in any way engages the tie plate. Such clamps are designed to provide a resilient containment of the railthat is-the length of portion 62 allows a slight springing motion allowing rail 50 to move slightlyin contrast to a rigid metal to metal fit wherein the only play or resiliency comes from the breaking down of the wood fibers such as when iron spikes are firmly secured to the rail.

FIG. 2 illustrates another embodiment of the inven-, tion wherein the non-metallic tie plate is cast with sloped sidewalls 30 and 40' which key into a similarly cut groove 4 in the time. The advantage of this particular construction is the locking effect created.

As an example of the invention, a urethane tie plate having the physical characteristics previously mentioned Was cast and bonded to a tie in similar fashion to FIG. 1. This construction was then tested in a machine provided for such purposes by the American Railroad Association to artificially simulates the stresses and strains normally encountered in normal service. The tie and tie plate bonded thereto were subjected to 2 /2 million cycles in this machine representing a lifetime of wear. The rail was then removed from the tie and the surface of the tie plate examined for abrasive wear. The wear on the Polyurethane tie plate (reflecting a life-time of use) was so slight as to be only barely perceptible. The urethane to tie bond was also examined and was also found to be excellent.

To further test the eflicacy of the invention, it was sub jected to a second test known as the AITC Durability Test 110. This test consists of immersing the tie in water and while immersed subjecting the tie having the urethane tie plate bonded thereto to a vacuum to remove all air from the wood and then subjecting the so evacuated tie to a pressure cycle to drive water into the wood replacing the air removed under vacuum. The tie and t'e plate are then again subjected to the vacuum and again to the water pressure. The cycle is repeated three times after which the wood is dried to constant weight. This test is reported to simulate the effects of very damp weather followed by very dry, hot weather causing the swelling and subsequent shrinkage of the wood fibers. At the end of this period, the bond was again inspected as well as the condit'on of the urethane tie plate itself. The bond was found to have held very well and the urethane showed no deleterious effects from the vacuum and water pressure treatment.

The epoxy tie plate previously referred to was also tested in the same manner with equally good results.

A third test was used to study the effects of temperature upon the invention both as to durability and as to swelling and contracting by testing the strength of the bond. In this test, the tie and bonded tie plate were subjected to minus 70 C. in a C0 ice chest. The tie and tie plate were held at such temperature for 24 to 48 hours (to insure that the entire tie reached this temperature) and then brought back up to ambient temperatures. This was done three times to study the effects of such temperature cycles on the bond. The bond in this test also held excellently.

As an additional part of the above test the tie plate, when first removed from the ice chest, was subjected to a heavy striking force from the round end of a ball peen hammer to demonstrate its durability. It was found that the low temperature effect did not cause the tie plate to shatter.

The foregoing has described a novel rail supporting means which pa t a cushi n beneath the rail which is constructed of a material which is not chemically degraded by the rail and does not deleteriously aflect the tie. The plate is securely bonded to the tie and thus provides complete protection against the action of dirt and moisture which otherwise enters and acts on the interface between the tie plate and tie. The adhesive bond abrogates the need for mechanical fastening means between the tie plate and the tie which otherwise might act to break the protective seal between the tie and the tie plate. The bond strengthens the wood fibers adjacent to the interface by hardening them. Furthermore, the tie plate securely locates the rail on the tie against lateral thrust, providing a cushion and gage maintaining support between the tie and the rail on each side of the rail flange which is spread across the entire width of the tie and tie plate in marked contrast to the one or two spikes used in the prior art.

We claim:

1. Rail support means comprising a generally rectangular wood railroad tie having an upper surface thereon, a non-metallic tie plate comprising a non-flowable crosslinked plastic material having a tensile strength of at least 4000 p.s.i., and being substantially non-permanently deformable, and being adhesively bonded to the wood on said upper surface to completely seal the interface between tie and tie plate, and to support a rail which is secured to said tie and said tie plate by holding means spaced apart from said tie plate.

2. The rail support means of claim 1 wherein a groove is cut into the top surface of said wooden tie, said groove having a width substantially equal to the width of said tie plate to enable the tie plate to be inserted in said groove, the side walls of said groove acting to support the tie plate against lateral movement relative to said tie.

3. The rail support of claim 2 wherein said tie plate has a slot cut therein corresponding substantially to the width of the base portion of a rail to thereby provide bands of material on both sides of the rail flange, between the flange and both sidewalls of the groove respectively to retain the rail against lateral thrust.

4. The rail support means of claim 1 wherein the nonmetallic tie plate is an epoxy resin material characterized by the following physical properties:

bonded to the wooden tie by an adhesive selected from the class consisting of resoreinol glues and epoxy cement, said polyurethane tie plate being characterized by the following physical properties:

Tensile strength (ultimate) p.s.i 4000-8000 Elongation at break "percent" 200-600 Modulus at elongation p.s.i 2400-3800 300% elongation p.s.i 2400-3800 Compressive strength at- 10% deflection p.s.i 700-1500 20% deflection p.s.i 1300-2400 References Cited UNITED STATES PATENTS 1,088,062 2/ 1914 Chipley 238-285 3,055,590 9/1962 Mitman 238383 3,100,080 8/1963 Fiechter 238-383 3,206,123 9/1965 Baker 238349 3,254,840 6/1966 Chartet 238349 3,298,607 1/ 1967 Grofl 238243 ARTHUR L. LA POINT, Primary Examiner.

R. A. BERTSCH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,358,925 December 19, 1967 Charles J. Pennino et a1. It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 23, "p.s.i---2400-3800" should read p.s.i-

Signed and sealed this 12th day of August 1969.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. RAIL SUPPORT MEANS COMPRISING A GENERALLY RECTANGULAR WOOD RAILROAD TIE HAVING AN UPPER SURFACE THEREON, A NON-METALLIC TIE PLATE COMPRISING A NON-FLOWABLE CROSSLINKED PLASTIC MATERIAL HAVING A TENSILE STRENGTH OF AT LEAST 4000 P.S.I., AND BEING SUBSTANTIALLY NON-PERMANENTLY DEFORMABLE, AND BEING ADHESIVELY BONDED TO THE WOOD ON SAID UPPER SURFACE TO COMPLETELY SEAL THE INTERFACE BETWEEN TIE AND TIE PLATE, AND TO SUPPORT A RAIL WHICH IS SECURED TO SAID TIE AND SAID TIE PLATE BY HOLDING MEANS SPACED APART FROM SAID TIE PLATE. 